1. Field of the Invention
The present invention relates to a location information conversion device, control method therefor, a location information providing system using them, and control method therefor. More particularly, the present invention relates to a location information conversion system which converts input location information into location information of a predetermined accuracy and produces output, and a location information providing system using the location information conversion system.
2. Description of the Prior Art
Recent years, various services have been implemented using location information on users of portable terminals. For example, a service is available which provides information related to an area around the user's current location. Configuration of a location information providing system for this conventional service is shown in FIG. 26. In the figure, reference numeral 540 denotes a portable terminal and reference numerals 551, 552, 553, . . . , and 55n denote location-related information providers that provide information to the portable terminal 540. The portable terminal 540 and the location-related information providers 551, 552, 553, . . . , 55n are connected via a mobile communications network 560.
As the user uses the portable terminal 540, location information which indicates the current location of the user is sent to the location-related information providers 551, 552, 553, . . . , 55n via the mobile communications network 560. Then, the user can readily obtain information relevant to an area around that location, including shop information about eating and drinking places, amusement facilities, and the like, traffic information, and information about nearby stations, which is sent to the user's portable terminal 540 from the location-related information providers 551, 552, 553, . . . , 55n via the mobile communications network 560.
The portable terminal 540 used for this service is equipped with a location information conversion device 500 to send the location-related information which indicates the current location of the user to the location-related information providers 551, 552, 553, . . . , 55n. Internal configuration of the location information conversion device 500 is shown in FIG. 27, in which the location information conversion device 500 consists of an input/output section 510 which inputs and outputs information from/to the outside, a location measurement section 520 which acquires location information about a search object, and a location information providing section 530 which provides location information to the outside.
Incidentally, possible methods for acquiring location information in the location measurement section 520 include methods which employ GPS (Global Positioning System), methods which employ a portable telephone network, and methods which employ wireless tags and tag detectors.
Next, operation of the conventional location information conversion device will be described in detail with reference to FIG. 27. The location information conversion device 500 receives a request for location information from outside via the input/output section 510. Then, the location information providing section 530 acquires location information about a search object from the location measurement section 520 and outputs it to the requesting party via the input/output section 510. In this way, it is possible to provide location information about a search object in response to a request from the outside.
With the conventional service described above, location-related information on the user is conveyed as it is to the location-related information providers 551, 552, 553, . . . , 55n via the mobile communications network 560. Consequently, information about whereabouts of the user utilizing the portable terminal 540 is fully conveyed to the location-related information providers unless some measures are taken. This raises a problem of privacy protection of the user with respect to his/her location, especially when the object whose location information is retrieved is a human being.
To protect privacy in the use of the conventional location information conversion device 500, location information about a search object is provided to outsiders only when the search object is outside a particular area designated in advance, as disclosed in Japanese Patent No. 3111063.
However, a system in which location information is provided to location-related information providers only when the searcher is outside a particular area as disclosed in the above patent has the drawback that when the searcher is within the particular area, the searcher cannot receive location-related information, and thus cannot get the full benefits of the location-related information providing service. It also has the drawback that when the searcher is outside the particular area, privacy cannot be protected at all.
Also, when actually receiving the service, the searcher may want to vary the accuracy of his/her location information to be conveyed to location-related information providers according to his/her present location. For example, some searchers do not want to send detailed location information around their houses, but want to send detailed location information in sightseeing areas or other travel destinations they are not familiar with in order to be provided with detailed location-related information.
In such a case, the conventional location information conversion device which gives no consideration to privacy protection has the problem that since it conveys location information about the search object to the location-related information providers as it is, the searcher's location information is conveyed to the location-related information providers in detail even if the searcher does not desire to be provided with detailed location-related information.
Also, the position detection system disclosed in the patent described above only judges whether to provide location information to outsiders depending on whether the search object is within a particular area designated in advance. It is not possible to set the accuracy of location information to be provided to outsiders or change the accuracy according to the present location of the search object.